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Just bought the car, & it had that notorious surging/revving problem where after reaching operating temperature, the engine would rev between around 900 & 1500 RPM.

I bravely(perhaps foolishly) decided to try adjusting the Idle Air Stabalizer Valve screw (remembering where & how much I was turning) & I found that with 2 turnsclockwise(into the body of the valve) the engine is now settled around 900 RPM.
Much better I think than that other buisines!
I hope it stays!

Just bought the car, & it had that notorious surging/revving problem where after reaching operating temperature, the engine would rev between around 900 & 1500 RPM.

I bravely(perhaps foolishly) decided to try adjusting the Idle Air Stabalizer Valve screw (remembering where & how much I was turning) & I found that with 2 turnsclockwise(into the body of the valve) the engine is now settled around 900 RPM.
Much better I think than that other buisines!
I hope it stays!

Cheers!
Rich

This morning it seems to still surge, but not quite so bad.
Guess I'll be digging in more. ECU?
I haven't changed basic stuff yet, like plugs, cap, & even the air filter so guess I'll
hold offf on positive results till I change that stuff.

That has to be one of the best write ups I've ever seen. I've had an idle problem for a couple of years now and I hope I can find my reason in here. Is there anyway that the ICV or ICM could cause a missfire at idle. My car runs fine when moving, just a bad missfire when I stop.

I had that problem on my previous 325e.I replaced the o2 sensor,and the problem was gone.If your car has rough idling,hesitating,other related problem.Then its more than likely the 02 sensor in your exhaust.

buy a haynes or bentley repair manual (20-40 bucks) and get out your voltometer and check the ohm's and voltage resistance in these things throttle position switch ,air flow meter,and then check your feul pressure and your fuel pressure regulator . Oh and try running your car at night looking at the plug wires this way you can see if a wire is grounding to the motor and some bosch plat +4's would be nice, i havn't found an rough idle yet that a $6.99 spark plug couldn't fix.good luck p.s.if all else fails check compression